These days, touch detection devices capable of detecting externally approaching objects referred to as so-called touch panels are gathering attention. A touch panel is attached or integrated onto a display such as a liquid crystal display. A liquid crystal display with a touch panel being attached or integrated onto the display in this manner, namely a liquid crystal display with touch detection functions, displays images of various buttons or the like on the display, and detects with a touch panel that an external object has approached the button images. This makes it possible to use the touch panel as means for inputting information instead of normal mechanical buttons. Since such liquid crystal displays with touch detection functions do not necessary require means for inputting information such as keyboards or mice, their use is spreading not only for computers but also for portable information terminals such as portable phones.
As for detection methods for touch detection devices, there are various methods such as those of optical type, resistance type and electrostatic capacity type. Among these, touch detection devices of electrostatic capacity type have relatively simple structure and low power consumption, so that they are used in portable information terminals. Patent Document 1 (Japanese Patent Application Publication Laid-Open No. 2009-244958) and Patent Document 2 (Japanese Patent Application Publication Laid-Open No. 2013-182548) describe touch detection devices of electrostatic capacity type.